Circuit Board For LED

ABSTRACT

A submount comprising a chip mounting area, a first bonding pad and a connecting portion is provided. An LED chip is mounted on the chip mounting area. The first bonding pad is electrically connected to an electrode of the LED chip. The connecting portion has a first hollow portion and is disposed between the chip mounting area and the first bonding pad. The first hollow portion is located between the chip mounting area and the first bonding pad. The first hollow portion is located in a central region of the connecting portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application of U.S. patent application Ser. No. 12/404,350, filed on Mar. 16, 2009, entitled “Circuit Board for LED” which claim priority from Taiwan patent application TW097144357, filed Nov. 17, 2008, which applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a circuit board, and, particularly, to a circuit board for LED (light emitting diode).

DESCRIPTION OF THE PRIOR ART

The LED package mainly includes processes such as chip mounting, wire bonding, glue molding, cutting, test, and packing. The LED is allowed to be integrated with other electric circuit, as well as supported and protected.

In the chip mounting process, the LED will be fixed on the circuit board. Generally, an insulating adhesive is used for bonding the LED, as shown in FIG. 1. FIG. 1 shows a wiring diagram of a conventional circuit board for LED. FIG. 1 shows a circuit board 10 for LED. The circuit board 10 has a chip mounting area 11 and a wire bonding area 13. The chip mounting area 11 is coated with an insulating adhesive to bond an LED 15 onto the chip mounting area 11. Thereafter, one electrode of the LED is electrically connected with the wire bonding area through a wire by bonding. However, the adhesive tends to flow along the shape of the wire bonding area and to the location for bonding the wire on the wire bonding area, due to the low viscosity of the adhesive. As a result, the wire can not electrically connect the electrode of the LED and the wire bonding area 13 having the insulating adhesive thereon according to a predetermined design. Such situation will lead to a poor reliability for the packaging process.

FIG. 2 shows a wiring diagram of another conventional circuit board for LED. FIG. 2 shows the circuit board 20 for LED. The circuit board 20 has a chip mounting area 21, wire bonding areas 22 and 23, and four through holes 26, 27, 28, and 29. An LED 25 is electrically connected by bonding to the wire bonding areas 22 and 23 through a wire. The wire bonding area 22 connects the through holes 26 and 27 and the wire bonding area 23 connects the through holes 28 and 29, to allow two electrodes of the LED 25 to be electrically connected with the internal circuit of the circuit board 20. However, with such wiring scheme, the through holes occupy most area of the circuit board 20, and accordingly the amount of the LEDs 25 mounted on the circuit board 20 is limited.

Therefore, an improved circuit board for LED is needed to solve the aforesaid problems, such as adhesive overflow and excessive area occupied by the through holes on the circuit board for LED.

SUMMARY OF THE PRESENT DISCLOSURE

One object of the present disclosure is to provide a circuit board for LED to solve the problem of adhesive overflow and to increase the adhesion between the circuit board and the encapsulating material, such that the reliability of the packaging process can be increased.

Another object of the present disclosure is to provide a circuit board for LED, to increase the amount of LEDs mounted on a single circuit board.

According to the aforesaid object of the present disclosure, a circuit board for LED is provided, which includes a chip mounting area, a first bonding pad, and a connecting portion. The LED is mounted on the chip mounting area through an adhesive applied on the chip mounting area. The first bonding pad is electrically connected to an electrode of the LED. The connecting portion is disposed between the chip mounting area and the first bonding pad. One side of the connecting portion is connected with the chip mounting area, and another side of the connecting portion is connected with the first bonding pad. The connecting portion has a hollow portion which can prevent the adhesive from flowing to the first bonding pad.

Furthermore, in one preferred embodiment of the present disclosure, the hollow portion may be selectively disposed in an edge portion of the connecting portion or in a central region of the connecting portion.

In addition, in one preferred embodiment of the present disclosure, the circuit board for LED may further include a second bonding pad and at least two through holes. The second bonding pad is electrically connected to another electrode of the LED. The first bonding pad and the second bonding pad are electrically connected to an internal circuit layer of the circuit board for LED through the through holes respectively.

According to another object of the present disclosure, a circuit board for LED is provided. At least two LEDs are mounted on the circuit board for LED. The circuit board for LED includes at least two chip mounting areas, at least two bonding pads, at least two connecting portions, and at least two through holes. The at least two LEDs are mounted on the at least two chip mounting areas, respectively, through an adhesive applied on the chip mounting areas. Each first bonding pad is electrically connected to an electrode of each of the LEDs. The bonding pads are electrically connected to an internal circuit layer of the circuit board for LED through the through holes. Each of the connecting portions is disposed between each of the chip mounting areas and each of the first bonding pads. One side of each of the connecting portions is connected with each of the chip mounting areas, and another side of each of the connecting portions is connected with each of the first bonding pads. Each of the connecting portions has a hollow portion which prevents the adhesive from flowing to the bonding pad.

In another aspect, in another preferred embodiment according to the present disclosure, the circuit board for LED may further includes at least two second bonding pads and at least two through holes. Each second bonding pad is electrically connected to another electrode of each LED. The second bonding pads are electrically connected to the internal circuit layer of the circuit board for LED through the through holes.

In view of the above description, by utilizing the circuit board for LED according to the present disclosure, the adhesive overflow to the bonding pads can be prevented, the amount of the LEDs mounted on one single circuit board can be increased, and the adhesion between the circuit board and the encapsulating material can be enhanced, such that the improvement of the reliability of the packaging process and the increase of the production capacity can be accomplished by the circuit board for LED of the present disclosure.

These and other objectives of the present disclosure will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

In one embodiment of the present disclosure, a submount comprising a chip mounting area, a first bonding pad and a connecting portion is provided. An LED chip is mounted on the chip mounting area. The first bonding pad is electrically connected to an electrode of the LED chip. The connecting portion having a first hollow portion and disposed between the chip mounting area and the first bonding pad. The connecting portion electrically connects the chip mounting area and the first bonding pad. One side of the connecting portion is connected with the chip mounting area. Another side of the connecting portion is connected with the first bonding pad. The first hollow portion is located between the chip mounting area and the first bonding pad. The first hollow portion is located in a central region of the connecting portion.

In one embodiment of the present disclosure, an LED package comprising an LED chip and a submount is provided. The submount comprises a chip mounting area, a first bonding pad and a connecting portion. The LED chip is mounted on the chip mounting area. The first bonding pad is electrically connected to an electrode of the LED chip. The connecting portion having a first hollow portion and disposed between the chip mounting area and the first bonding pad. The connecting portion electrically connects the chip mounting area and the first bonding pad. One side of the connecting portion is connected with the chip mounting area. Another side of the connecting portion is connected with the first bonding pad. The first hollow portion is located between the chip mounting area and the first bonding pad. The first hollow portion is located in a central region of the connecting portion.

The submount further comprises a second bonding pad and at least two through holes. The second bonding pad is electrically connected to another electrode of the LED chip, and the first bonding pad and the second bonding pad are electrically connected with an internal circuit layer of the submount through the through holes, respectively. The LED package further comprises two adjacent corners in which the two through holes are correspondingly disposed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wiring diagram of a conventional circuit board for LED.

FIG. 2 shows a wiring diagram of another conventional circuit board for LED.

FIG. 3 a illustrates a wiring diagram of a preferred embodiment of the circuit board for LED according to the present disclosure.

FIG. 3 b illustrates a cross-sectional view of the circuit board for LED along the line AA′ in FIG. 3 a.

FIG. 4 illustrates a wiring diagram of another preferred embodiment of the circuit board for LED according to the present disclosure.

FIG. 5 illustrates a wiring diagram of still another preferred embodiment of the circuit board for LED according to the present disclosure.

FIG. 6 illustrates a wiring diagram of further another preferred embodiment of the circuit board for LED according to the present disclosure.

FIG. 7 illustrates a wiring diagram of yet another preferred embodiment of the circuit board for LED according to the present disclosure.

DETAILED DESCRIPTION

FIG. 3 a illustrates a wiring diagram of one preferred embodiment of the circuit board for LED according to the present disclosure. FIG. 3 a, in this preferred embodiment, shows an LED 90 being mounted on a circuit board 30 for LED. The circuit board 30 for LED includes a chip mounting area 31, bonding pads 33 and 34, and a connecting portion 35. In the chip mounting process for packaging the LED 90, the surface of the chip mounting area 31 will be coated with an insulating adhesive for mounting the LED 90. In a subsequent wire bonding process, one end of a wire 37 is connected by bonding to, for example, a negative electrode of the LED 90, and another end of the wire 37 is connected by bonding to the bonding pad 33, to allow the negative electrode of the LED 90 to be electrically connected to the bonding pad 33. On the other hand, one end of a wire 38 is connected by bonding to a positive electrode of LED 90, and another end of the wire 38 is connected by bonding to the bonding pad 34, to allow the positive electrode of the LED 90 to be electrically connected to the bonding pad 34. The connecting portion 35 electrically connects the chip mounting area 31 and the bonding pad 33. Two triangular hollow portions are located on edges of the connecting portion 35, respectively. Since the two triangular hollow portions each are in a trench shape, as the insulating adhesive flows toward the bonding pad 33, the insulating adhesive will stay in the triangular hollow portions and not flow onto the bonding pad 33. Accordingly, the situation that the insulating adhesive impedes the wire bonding can be effectively avoided.

In addition, in the subsequent mold compression, the triangular hollow portion of the connecting portion 35 may increase the contact area between the encapsulating material and the circuit board 30 for LED, such that the adhesion between the circuit board 30 for LED and the encapsulating material can be enhanced.

Therefore, the circuit board 30 for LED of the preferred embodiment can effectively prevent the overflow of the insulation adhesive and improve the reliability of the packaging process.

FIG. 3 b illustrates a cross-sectional view of the circuit board for LED along the line AA′ in FIG. 3 a. FIGS. 3 a and 3 b show the triangular hollow portion 36 of the connecting portion 35 is in a trench shape. Accordingly, when the insulating adhesive flows toward the bonding pad 33, the insulating adhesive will stop flowing and stay in the triangular hollow portion 36 and not flow onto the bonding pad 33, such that the situation that the insulating adhesive impedes the wire bonding can be effectively avoided.

FIG. 4 illustrates a wiring diagram of another preferred embodiment of the circuit board for LED according to the present disclosure. FIG. 4 shows an LED 90 being mounted on a circuit board 40. The circuit board 40 for LED includes a chip mounting area 41, bonding pads 43 and 44, and a connecting portion 45. The circuit board 40 for LED differs from the circuit board 30 for LED in that the connecting portion 45 has a trench-shaped hollow portion in the edge region thereof. The hollow portion is in a trench shape, and the insulation adhesive will stop flowing and stay in this hollow portion and not flow onto the bonding pad 43.

FIG. 5 illustrates a wiring diagram of still another preferred embodiment of the circuit board for LED according to the present disclosure. FIG. 5 shows an LED 90 being mounted on a circuit board 50 for LED. The circuit board 50 for LED includes a chip mounting area 51, bonding pads 53 and 54, and a connecting portion 55. The circuit board 50 for LED differs from the circuit board 30 for LED in that the connecting portion 55 has a rectangular hollow portion located in the center region thereof. The rectangular hollow portion is in a trench shape, and the insulation adhesive will stop flowing and stay in this rectangular hollow portion and not flow onto the bonding pad 53.

FIG. 6 illustrates a wiring diagram of further another preferred embodiment of the circuit board for LED according to the present disclosure. FIG. 6, in this preferred embodiment, shows LEDs 90 a and 90 b being mounted on a circuit board 60 for LED. The circuit board 60 for LED includes chip mounting areas 61 a and 61 b, bonding pads 63 a and 63 b, connecting portions 65 a and 65 b, and through holes 67 and 69. Likewise, in the chip mounting process for packaging the LEDs 90 a and 90 b, the surface of the chip mounting areas 61 a and 61 b will be coated with an insulating adhesive for mounting the LEDs 90 a and 90 b, respectively. In a subsequent wire bonding process, one end of a wire is bonded to an electrode of the LED 90 a, and the other end of the wire is bonded to the bonding pad 63 a. One end of another wire is bonded to an electrode of the LED 90 b, and the other end of the wire is bonded by to the bonding pad 63 b. Thus, the negative electrodes of the LEDs 90 a and 90 b are allowed to be electrically connected to the bonding pads 63 a and 63 b, respectively. In addition, the bonding pads 63 a and 63 b are electrically connected to an internal circuit layer of the circuit board 60 for LED through the through holes 67 and 69, respectively. The connecting portions 65 a and 65 b electrically connect with the chip mounting areas 61 a and 61 b and the bonding pads 63 a and 63 b, respectively. Each of the connecting portions 65 a and 65 b has a triangular hollow portion in an edge region thereof. Since the two triangular hollow portions each are in a trench shape, as the insulating adhesive flows toward the bonding pad 63 a or 63 b, the insulating adhesive will stay in the triangular hollow portions and not flow onto the bonding pads 63 a and 63 b. Accordingly, the situation that the insulating adhesive impedes the wire bonding by soldering can be effectively avoided.

In a packaging process, using the circuit board 60 for LED can effectively prevent the insulating adhesive from impeding the wire bonding, and in the other hand, since the LEDs 90 a and 90 b commonly use the through holes 67 and 69, the area occupied by the through holes 67 and 69 on the circuit board 60 for LED can be reduced, such that the amount of LEDs disposed on the circuit board 60 for LED can be increased. Furthermore, the area occupied by the through holes 67 and 69 may be further effectively reduced through the utilization of advanced laser technology to form the through holes 67 and 69 with decreased diameters in the embodiment of the present disclosure.

The circuit board 60 for LED is cut into two pieces of circuit boards 70 (as shown in FIG. 7) in a cutting process for subsequent package tests.

FIG. 7 illustrates a wiring diagram of yet another preferred embodiment of the circuit board for LED according to the present disclosure. FIG. 7 shows the LED 90 being bonded to the circuit board 70 for LED, which includes a chip mounting area 71, bonding pads 73 and 74, and a connecting portion 75. In addition, an element 76 for voltage regulator may be optionally disposed on the circuit board 70 for LED for connecting with a voltage regulator to reduce electromagnetic interference.

The connecting portions 65 a and 65 b, and 75 of the circuit boards 60, 70 for LED each may have a triangular hollow portion as the aforesaid or may optionally have a trench-shaped hollow portion in an edge region of the connecting portion or a hollow portion in the central region of the connecting portion. However, it should be noted that the structures of the connecting 65 a and 65 b are not limited to the structures mentioned in the aforesaid embodiments. Those ordinarily skilled in the art may change the shape and the location of the hollow portion of the connecting portion without departing from the spirit and the scope of the present disclosure.

In view of the above-described preferred embodiments of the present disclosure, it is advantageous to utilize the circuit board for LED according to the present disclosure that the adhesive overflow can be prevented, the amount of the LEDs mounted on one single circuit board can be increased, the adhesion of the circuit board between the encapsulating material can be enhanced, the reliability of the packaging process can be improved, and the production capacity can be increased.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the present disclosure. 

1. A submount comprising: a chip mounting area configured for an LED chip to be mounted thereon; a first bonding pad that, when the LED chip is mounted on the chip mounting area, electrically connects to an electrode of the LED chip; and a connecting portion having a first hollow portion and disposed between the chip mounting area and the first bonding pad, the connecting portion electrically connecting the chip mounting area and the first bonding pad with a first side of the connecting portion connected with the chip mounting area and a second side of the connecting portion connected with the first bonding pad, the first hollow portion being located between the chip mounting area and the first bonding pad, the first hollow portion being located in a central region of the connecting portion.
 2. The submount of claim 1, further comprising a second bonding pad and at least two through holes, wherein the second bonding pad is electrically connected to another electrode of the LED chip, and wherein the first bonding pad and the second bonding pad are electrically connected with an internal circuit layer of the submount via the through holes, respectively.
 3. The submount of claim 2, wherein the connecting portion further has a second hollow portion located in an edge region of the connecting portion.
 4. The submount of claim 1, wherein the connecting portion further has a second hollow portion located in a central region of the connecting portion.
 5. The submount of claim 1, wherein a surface of the chip mounting area is coated with an insulating adhesive for mounting the LED.
 6. The submount of claim 1, wherein the first hollow portion is a rectangular hollow portion.
 7. The submount of claim 2, wherein the first hollow portion is a rectangular hollow portion.
 8. The submount of claim 3, wherein the second hollow portion is a triangular hollow portion.
 9. The submount of claim 4, wherein the second hollow portion is a triangular hollow portion.
 10. The submount of claim 3, wherein the second hollow portion is a rectangular hollow portion.
 11. The submount of claim 4, wherein the second hollow portion is a rectangular hollow portion.
 12. A light-emitting diode (LED) package, comprising: an LED chip; and a submount comprising: a chip mounting area on which the LED chip is mounted; a first bonding pad electrically connected to an electrode of the LED chip; and a connecting portion having a first hollow portion and disposed between the chip mounting area and the first bonding pad, wherein the connecting portion electrically connects the chip mounting area and the first bonding pad with one side of the connecting portion connected with the chip mounting area and another side of the connecting portion connected with the first bonding pad, wherein the first hollow portion is located between the chip mounting area and the first bonding pad, and wherein the first hollow portion is located in a central region of the connecting portion.
 13. The LED package of claim 12, wherein the submount further comprises a second bonding pad and at least two through holes, wherein the second bonding pad is electrically connected to another electrode of the LED chip, and wherein the first bonding pad and the second bonding pad are electrically connected with an internal circuit layer of the submount via the through holes, respectively.
 14. The LED package of claim 13, further comprising two adjacent corners in which the two through holes are correspondingly disposed.
 15. The LED package of claim 13, wherein the connecting portion further has a second hollow portion located in an edge region of the connecting portion.
 16. The LED package of claim 14, wherein the second hollow portion is a triangular hollow portion or a rectangular hollow portion.
 17. The LED package of claim 12, wherein the connecting portion further has a second hollow portion located in an edge region of the connecting portion.
 18. The LED package of claim 17, wherein the second hollow portion is a triangular hollow portion or a rectangular hollow portion.
 19. The LED package of claim 12, wherein the first hollow portion is a rectangular hollow portion.
 20. The LED package of claim 13, wherein the first hollow portion is a rectangular hollow portion. 